The present invention relates to plastic bags and packages of the type in which food products are packaged for sale to consumers. More particularly the present invention relates to recloseable zippered packaging that is of a type that is particularly well suited for use for products such as chips and other salty snacks. Such packages are conventionally formed of a laminated plastic film material, the various plies of the laminate having desired barrier and other properties to protect the bag contents and provide a handsome package.
The conventional non-zippered chip package is designed to enable the consumer to open the package by gripping the front and rear walls of the package with thumb and forefinger of each hand, pinching some of the wall on each side of the bag inside the thumb and forefinger, and simply pulling the walls apart. This results in a de-lamination of the bag at the top seal, pulling the top seal apart and thereby providing access to the contents of the bag through the open top. Such bags are designed to delaminate with approximately 800 grams of pull force.
The benefits of adding a zipper feature to such packaging is readily apparent. One of the most obvious benefits being that any unused portion of the bag may be easily stored and protected simply by closing the zipper after initially opening the package. The problem encountered, however, is that the pull force necessary to delaminate the top seal, when applied to the package below the zipper, tends to delaminate the zipper from the bag walls, rendering the zipper useless. The addition of a zipper to such packaging has thus required that the packaging be designed to require the user to depart from the conventional "pinch and pull" technique of initially opening the sealed package with which the public has become acquainted. As a result, zippered packaging has met with only limited success for chips and other similar products, due, at least in part, to the reluctance of producers to sacrifice the accepted "pinch and pull" opening feature of the packaging in favor of a reclosable feature.